Food waste is a pressing global concern, encompassing organic waste generated throughout the collection, processing, and distribution of food products. This waste stems from poor practices at both domestic and commercial levels. Studies suggest that around 45% of food produced is lost or wasted before and after it reaches consumers, spanning all stages of the food supply chain, including primary production, post-harvest handling, processing, distribution, and consumption.
Current strategies outlined by the World Health Organization (WHO) and the European Union (EU) emphasize the transition to a circular economy as a strategic approach for sustainable growth and improved health outcomes. This entails safeguarding the environment and its resources while mitigating the effects of climate change.
To fulfill these goals, the significant volumes of inedible biomass generated along the food chain should be repurposed as valuable by-products, thereby giving them new life. The EU offers legislative backing to prevent, reduce, and manage food waste. Directive 2008/98/EC establishes a hierarchy for effective waste management, prioritizing prevention as the primary objective. Governments are encouraged to minimize waste generation first, followed by options such as reuse, recycling, recovery, and disposal.
In this context, repurposing agro-industrial by-products presents an opportunity to access renewable and cost-effective sources of various molecules, including peptides, proteins, fibers, polysaccharides, fatty acids, phenolic compounds, and more. These can be extracted and utilized as bioactive ingredients in innovative and sustainable products across food, feed, and cosmetics applications. Particularly noteworthy are their bioactivities associated with immune response modulation, oxidative stress reduction, prevention of cardiovascular and age-related diseases, tumor prevention, and antioxidant and antimicrobial effects.
Types of Food By-Products
Food by-products can be classified into different categories, each possessing distinct characteristics and potential for valorization.
Below are some of the main types of food by-products:
Plant by-products generated during post-harvest processing contribute to billions of tons of food processing waste annually, out of a total of 1.6 billion tons of waste. The composition of plant waste varies from country to region due to factors such as dietary habits, environmental conditions, and levels of local agricultural development (FAO, 2013). Globally, cereals and vegetables account for the majority of food loss (71%), followed by fruit (25%), and oilseeds and legumes (4%).
High-value compounds (HVCs) extracted from food processing waste streams can be categorized into macromolecules, such as proteins and polysaccharides, or small molecule compounds like vitamins, antioxidants, and micronutrients. The nature of food by-products determines the target compounds that can be recovered and the optimal recovery strategy. For instance, dietary fiber like wheat bran is commonly extracted from plant-based food by-products, while proteins like collagen are typically obtained from animal-origin food waste.
The identification, quantification, and extraction of these compounds, along with evaluating their effects, have become crucial areas of research, uncovering their antioxidant, antimicrobial, anti-inflammatory, immunomodulatory, and anti-tumor properties.
Plant HVCs are categorized into two groups: essential (primary) and non-essential (secondary) metabolites. Essential metabolites primarily consist of vitamins and minerals that prevent deficiency diseases and maintain specific biochemical processes. Secondary metabolites, such as phenols, carotenoids, phytosterols, saponins, essential oils, and phytic acids, play vital biological roles in promoting and sustaining cellular health, leading to enhanced longevity. Fruit, vegetable, and cereal by-products are particularly rich in phenols, carotenoids, phytosterols, polysaccharides, proteins, and fatty acids.
Valorization of agri-food by-products/wastes
As previously mentioned, the agri-food supply chain is a strategic market with a view to implementing circular models within current economic systems.
Fortunately, there are already several virtuous applications within this context, which if applied correctly can offer significant advantages to the involved companies from various perspectives:
Bioactive effects of HVCs extracted from agri-food by-products/wastes
The Institute of Agricultural Biology and Biotechnology of CNR in Pisa has been involved in several studies focusing on characterizing and valorizing agri-food waste. Specifically, it has played a key role in assessing the phenolic composition, antimicrobial activity, and antioxidant activity of extracts from seeds of four Vitis specie (V. riparia Michx., V. californica Benth., V. amurensis Rupr. and V. vinifera L.). Furthermore, within the project “ON Foods – Research and innovation network on food and nutrition Sustainability, Safety and Security – Working ON Foods” funded by the European Union – NextGeneration EU – as part of the National Recovery and Resilience Plan (PNRR) and in collaboration with colleagues from the Institute of BioEconomy (IBE), who have developed an efficient, economical and fast process to extract bioactive and functional compounds in water, without solvents, through controlled hydrodynamic cavitation, we are working on the characterization the profile of the phenolic compounds of extracts obtained from orange (Citrus sinensis) and pomegranate (Punica granatum) waste, the evaluation of their safety through toxicity studies, as well as the bioavailability of the identified bioactive compounds. Research is currently ongoing to assess its antioxidant and anti-inflammatory properties, as well as its effectiveness in mitigating the primary cardiovascular risk factors linked to metabolic disorders.
Authors: Luisa Pozzo Andrea Vornoli
